I'd definitely agree with you on that. I think one of Persona's central themes is the manner in which people hide parts of themselves from those around them, so I guess it would make sense that the characters remain somewhat ambiguous. I'm fairly certain that Alma and Elisabet are the same person, but I don't think I'll ever know which is true: that Alma represents Elisabet's inner self or that Elisabet represents Alma's inner self.
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"Puns are the highest form of literature." -Alfred Hitchcock
"Puns are the highest form of literature." -Alfred Hitchcock